1. Technical Field
The present invention relates to a system and method for controlling an internal combustion engine.
2. Background Art
Faced with stricter emissions standards, new and increasingly sensitive combustion modes, e.g. low temperature combustion (LTC), have been developed to reduce the exhaust emissions of internal combustion engines. However, these combustion modes tend to be less robust than standard diesel combustion modes in regards to errors or deviations between the desired and actual composition of the intake gas. Such deviations are difficult to overcome during transient operating phases in which EGR (exhaust gas recirculation) rate and/or the intake pressure are commanded to change rapidly to accomplish the transition.
When actual FMAN (proportion of combusted gas in the intake on a mass basis) is less than desired FMAN, NOx emissions and combustion noise tend to be higher. When actual FMAN exceeds desired FMAN, combustion may become unstable, which can lead to loss of torque, increased fuel consumption, and increase emission of CO and unburned hydrocarbons.